This invention relates to a method and machine for assembling cables and pre-cast grids or blocks into articulated erosion control revetment mats or mattresses by arranging such blocks or grids in abutting relationship interconnected by the cables.
The present invention is adapted to be utilized in assembling or manufacturing articulated mat revetment consisting of grids of concrete or other suitable material cast or otherwise provided with one or more tunnels or holes passing horizontally through such grids. The grids are placed in a side by side or staggered abutting relationship, and cables pass through the grids to interconnect them into a mattress or mat. Although such mats may be assembled in situ at the location to be protected by revetment, such assembly is frequently difficult or impossible, such as in installations where all or a portion of the mat will be under water, and it is frequently undesirable for other reasons, such as the unavailability of labor at the site where revetment is to be installed or because of adverse onsite working conditions. Accordingly, such articulated mats are frequently produced adjacent to the installation site and then installed or are produced at a manufacturing location removed from the site where they are to be utilized and are transported to that site. Installation of a mat not assembled in situ is typically accomplished by lifting the mat by one or both ends of cables running therethrough and lowering the mat into place.
Examples of articulated revetment mats which may advantageously be manufactured in accordance with the present invention are disclosed in U.S. patent application Ser. No. 201,569 for "Revetment Grids and Mats" filed by John M. Scales Oct. 28, 1980, now U.S. Pat. No. 4,370,075, issued Jan. 25, 1983, which is particularly well suited for manufacture in accordance with the method and structure of the present invention; U.S. Pat. No. 4,227,829, for "Soil Erosion Prevention Blocks" issued Oct. 14, 1980, to Kossuth J. Landry; and Canadian Pat. No. 957,169, for "Covering Structure for Dams, Dikes and Other Hydrotechnical Constructions" issued Nov. 5, 1974, to E.A.H. Naue KG.
In the prior art practice, assembly of articulated revetment mats has been accomplished by placing grids to be assembled into a mat side by side or end to end on the ground or another supporting structure, and feeding or lacing cables through the colinear tunnels in such grids. Subassemblies of the mat may also first be produced, particularly in producing revetment having cables running in two directions through the mat and even rows and courses of grids, such as the Landry U.S. Pat. No. 4,227,829. For instance, a row of grids can be assembled on one or more cables, sometimes utilizing a conventional roller conveyor to support the grids during such assembly. Then, several rows of grids previously strung on cables can be laid side by side so that cables can be run at right angles to the first set of cables through the courses consisting of grids side by side in adjacent rows. This method of assembly is difficult and labor intensive because it requires a substantial amount grid handling and lifting and because it is difficult to accurately align grids in adjacent rows in order to feed cables through the appropriate holes or tunnels.